聚电解质膜PDAC/PSS诱导CaCO3结晶的研究

以模拟软体动物珍珠层的周期性基质控制形成过程制备仿生层状复合材料. 将聚苯乙烯磺酸钠(PSS)与聚二烯二甲基氯化铵(PDAC)用逐层浸渍的方法使其组装成多层膜, 用于诱导过饱和溶液中CaCO₃的结晶, 详细研究了膜紫外吸收随组装层数增加的线性变化. 扫描电镜和X射线衍射表征了晶体的形貌和结构. (PDAC/PSS)₁₅PDAC膜诱导获得的CaCO₃晶体为六面体结构, 晶体尺寸为30～40 μm; (PDAC/PSS)₁₅膜诱导CaCO₃结晶, 可以在膜表面获得形貌与珍珠层非常相似的CaCO₃晶体, 结晶10 h获得的晶片结构呈规则的六边形, 片尺寸约为10～20 μm. X射线衍射结果表明两种晶体的晶格结构与天然珍珠层差异明显, 说明静电作用为晶体形貌的主控因素之一, 但不是晶格结构的决定因素. 复合材料断面电镜照片表明其为层状结构.

Control of CaCO3 Crystal Growth on PDAC/PSS Self-Assembled Multilayers

Fabrication of biomimetic laminated composite by mimicking the cyclical matrix control process to form the highly structured Mollusca nacre was presented in this paper. (PDAC/PSS)_n self-assembled multilayers were built-up through alternative adsorption of polycation and polyanion to a substrate as matrices and their chemical structure was characterized by UV-vis absorption spectra. And then the deposition of CaCO₃ took place on the multilayers by dipping them into a supersaturated CaCO₃ solution. The crystals regulated by (PDAC/PSS)₁₅PDAC exhibited hexahedral shape and had a size of about 30～40 μm after 10 h deposition. Hexagonal CaCO₃ platelet crystals could be observed on (PDAC/PSS)₁₅ with a relative small size of 10～20 μm, which is very similar to the crystals existing in natural nacre. Therefore, CaCO₃ crystals with remarkable morphology similarity to natural biomineralization products were obtained in the presence of artificial polyanion. However, X-ray diffraction results indicated that crystal lattice of both the samples was different from any kind of natural nacre. Consequently, it might be supposed that electrostatic effect is one of the key factors in morphology control while the crystal lattice was determined by other factors. Furthermore, end surface SEM image of (PDAC/PSS)₁₅-CaCO₃ composite elucidated that alternation of multilayer growth and deposition of inorganic crystals coupled with morphology regulation could form laminated material.